Shaft seal

ABSTRACT

A shaft seal is disclosed in which the inner and outer lips of a U-cup sealing member are independently loaded against their respective contacted surfaces by loading rings independently biased in an axial direction.

iJn-ited States Patent 1111 3,630,531

[72] Inventor Pasquale C. Bondi [56] References Cited Revere, UNITEDSTATES PATENTS g 3 3 3 3,520,542 7/1970 Fruehauf 277/205x [73] AssigneeGeneral Electric Company Ste 2,546,961 4/1951 Amero 1. 277/62 X PrimaryExaminer-Samuel B. Rothberg SHAFT SEAL Att0meysDerek P. Lawrence, FrankL. N euhauser, Oscar B.

5 Claims 2 Drawing g Waddell, Joseph B. Forman and Edward S. Roman [52]US. Cl 277/117,

277/152 277/205 ABSTRACT: A shaft seal is disclosed in which the innerand [51] Ill-Cl outer p of a p Sealing member are independently 50 Fieldof Search 277/102, waded agamst respecme contacted Surfaces by loadmgrings independently biased in an axial direction.

PAIENiEnniczmn 3,630,531

INVENTOR. PASQUALE C. BOND! SHAFT SEAL BACKGROUND OF THE INVENTION AU-cup seal, which comprises a resilient inner lip adapted to seat on thecylindrical surface of a shaft and a resilient outer lip adapted to seaton a corresponding cylindrical surface in the shaft housing has, underprior practice, had its sealing lips loaded against their respectivecontacted surfaces by a single loading ring wedged between the inner andouter lips by an axially directed spring force. While operatingsatisfactorily in many situations, the loading method described hasseveral shortcomings. In the usual application of such a seal, the innerlip thereof is subject to sliding contact or rotating motion relative tothe shaft and the outer lip thereof is stationary in the shaft housing.The inner lip thus has a higher wear than does the outer lip, and afterwear on the inner sealing lip reaches a certain point, the singleloading ring can no longer wedge between the inner and outer lips farenough to adequately load the inner lip against its contacted surface.The seal thus tends to leak and must be replaced. A similar situationcan occur with new parts when the tolerance stackup in an assemblypermits the single-piece loading ring to wedge tightly against the outersealing lip or the inner sealing lip only. A third situation in whichthe prior art configuration is limited is that in which side loadsapplied to the shaft to be sealed tend to deform the inner lip of theU-cup seal, permitting fluid leakage between the seal and thecylindrical surface of the shaft.

In response to the limitations above noted, applicant has invented anovel combination which includes a U-cup sealing member and side-loadingmeans for loading the sealing lips of the sealing member against theirrespective contacted surfaces independently of the load on the othersealing lip. Thus, applicant has provided a combination which extendsseal life, is considerably less sensitive to tolerance stackups in theoverall actuator assembly, and exhibits an increased tolerance for sideloads on the sealed shaft.

BRIEF SUMMARY OF THE INVENTION Briefly stated, the invention is ashaft-sealing means which comprises a sealing member having a resilientinner annular lip and resilient outer annular lip and two independentlyacting bias means for biasing each of the said lips into sealing contactwith its contacted surface. In one embodiment, the bias means comprisesseparate inner and outer annular loading rings wherein the inner loadingring is nested within the outer loading ring and each bias meansincludes separate spring means for exerting axial force on the loadingrings.

BRIEF DESCRIPTION OF THE DRAWINGS While the specification concludes withclaims particularly pointing out and distinctly claiming the invention,it is believed that the invention will be more readily understandable byreference to the discussion below and the accompanying drawings inwhich:

FIG. I is a section view of an actuator embodying the sealing means ofthis invention; and

FIG. 2 is a fragmented section view on an enlarged scale of the sealingmeans of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. I shows an actuator whichcomprises a housing 12 having a cylindrical bore 14 and a piston 16slidably disposed in said bore 14. Housing 10 comprises barrel 18, endwalls 20, 22, and tie rods 24 clamping barrel 18 between end walls 20,22. An actuator rod 26 is connected to piston 16 and extends through endwall 20, end wall 20 being sealed against leakage around rod 26 by ashaft seal 28, which is the subject of this invention. A fluid inletport 30 is disposed at each end of bore 14 to admit pressurized fluidinto the actuator.

FIG. 2 illustrates the shaft seal means 28 in detail. Means 28 comprisesa sealing member 32 which is a standard U-cup device having an inner lip34 and an outer lip 36joined by an annular wall 37, the annular wall 37being axially supported by an end plate 38 which is fastened to end wall20. The resilient sealing lips 34, 36 are biased against theirrespective cylindrical contacted surfaces on shaft 26 and end wall 20 bybias means which comprise, in the case of the outer lip 36, a loadingring 40 and a spring 42, and in the case of the inner lip 34, an innerloading ring 44 and loading spring 46. Outer loading ring 40 is anannular ring which includes a frustoconical surface 48 to transmit aradial component of the axial force from spring 42 to lip 36. Innerloading ring 44 similarly includes a frustoconical surface 50 whichfunctions in the same manner to load inner lip 34 against shaft 26.

To minimize space requirements, the sealing means components referred toabove are constructed so that the inner lip 34 bias means are nestedwithin the bias means for outer lip 36. In the configuration shown,nesting is achieved by a construction in which the inner loading ring 44consists ofa cylindrical shell 52 which terminates on one end by thefrustoconical surface 50 and on the other end by an outwardly directedradial flange 54. Outer surface 55 of flange 54 is juxtaposed withspring 46, which in turn is supported in end wall 20 by a radial surface56. The bias means for outer sealing lip 36 includes an outer springsupport means 58 which comprises a cylindrical shell 60 axiallysupported by radial surface 56 and terminated on its axially unsupportedend by an inwardly directed flange 62, shell 60 being closely telescopedover the outer periphery of flange 54 and the inside diameter of flange62 being closely telescoped over the outer periphery of shell 52. Spring42 is axially supported by the outside surface 63 of flange 62, andouter loading ring 40 is telescoped over the end of inner loading ring44 cylindrical shell 52.

Any one of several types of springs could be specified for springs 42,46 to axially load loading rings 40, 44 against their respective sealinglips. However, in keeping with the object of compactness of theassembly, washer-type spring devices such as Belleville or Wave washersare preferred.

It can be seen by reference to the drawings and descriptions above thatthe sealing means detailed in FIG. 2 is particularly adapted forindependently loading the sealing lips 34, 36 of U- cup seal 32, andthat as a result wear of the inner surface of sealing lip 34 requiringcompensation by axial movement of loading ring 44 would receive suchcompensation without regard to wear or lack thereof on sealing lip 36.Similarly, any inaccuracies in machining frustoconical surfaces 48, 50or other component inaccuracies contributing to unfavorable assemblytolerance stackups will be compensated for by the independent loadingfeature of the configuration so that upon initial assembly andthroughout the wear life of seal 32 each of lips 34, 36 will beadequately biased against its respective contacted surface withoutregard to the dimensional condition of the other of the lips.

Having thus described a preferred embodiment of the invention, thoughnot exhaustive of all possible equivalents, what is desired to besecured by letters patent is that which appears in the claims below.

What is claimed is:

1. In a device having a cylindrical shaft extending through a housing, ashaft seal comprising:

a sealing member having a resilient inner annular lip and a resilientouter annular lip, said inner lip being adapted for sealing contact withthe cylindrical surface of said shaft and said outer lip being adaptedfor sealing contact with a cylindrical surface of said housing, at leastone of said lips being adapted for movable engagement with its contactedsurface;

an inner annular loading ring including a cylindrical shell terminatedon one end by a frustoconical surface in contact with said inner lip soas to push said lip toward contact with the surface of said shaft; andterminated on the other end by an outwardly directed annular flange;

inner spring means for maintaining contact between said innerfrustoconical surface and said inner lip;

an outer annular loading ring having a frustoconical surface in contactwith said outer lip so as to push said lip toward contact with thesurface of said housing; and

outer spring means for maintaining contact between said outerfrustoconical surface and said outer lip wherein said outer loading ringand outer spring means are telescoped over the cylinder portion of saidinner loading ring, said shaft seal further including support means foraxially supporting said outer spring means.

2. The shaft seal recited in claim 1 wherein said support means is anannular member comprising a cylindrical shell telescoped over saidoutwardly directed flange said cylindrical shell terminating with aninwardly directed annular flange telescoped over said cylindricalportion of said inner loading ring.

3. An actuator, comprising:

a housing,

a cylindrical shaft extending through one wall of said housing, meansfor moving said shaft relative to said housing, and a shaft sealcomprising;

a sealing member having a resilient inner annular lip and a resilientouter annular lip, said inner lip contacting a cylindrical surface ofsaid shaft and said outer lip contacting a cylindrical surface of saidhousing, at least one of said lips being adapted for movable engagementwith its contacted surface, said sealing member having an annular wallconnecting said lips and axially supported is said housing;

an inner annular loading ring including a cylindrical shell terminatedon one end by a frustoconical surface in contact with said inner lip soas to push said lip toward contact with the surface of said shaft andterminated on the other end by an outwardly directed annular flange;

an inner spring means contacting the outside surface of said flange andsupported by a radially oriented surface in said housing wherein saidinner spring means maintains contact between said inner frustoconicalsurface and said inner lip;

an outer annular loading ring having a frustoconical surface in contactwith said outer lip so as to push said lip toward contact with thesurface of said housing; and

an outer spring means for maintaining contact between said outerfrustoconical surface and said outer lip.

4. The actuator recited in claim 3 wherein the outer loading ring is anannular ring terminated on one end by said frustoconical surface andterminated on the other end by an annular surface normal to the axis ofsaid ring, the normal annular surface contacting the spring means forsaid outer loading ring, which spring means is supported by a supportmeans in contact with said radially oriented surface.

5. The actuator recited in claim 4 wherein said support means is anannular member comprising a cylindrical shell telescoped over saidoutwardly directed flange, said cylindrical shell terminating on its endremoved from said radially oriented surface with an inwardly directedannular flange, said inwardly directed flange supporting the outerloading ring spring means.

1. In a device having a cylindrical shaft extending through a housing, ashaft seal comprising: a sealing member having a resilient inner annularlip and a resilient outer annular lip, said inner lip being adapted forsealing contact with the cylindrical surface of said shaft and saidouter lip being adapted for sealing contact with a cylindrical surfaceof said housing, at least one of said lips being adapted for movableengagement with its contacted surface; an inner annular loading ringincluding a cylindrical shell terminated on one end by a frustoconicalsurface in contact with said inner lip so as to push said lip towardcontact with the surface of said shaft; and terminated on the other endby an outwardly directed annular flange; inner spring means formaintaining contact between said inner frustoconical surface and saidinner lip; an outer annular loading ring having a frustoconical surfacein contact with said outer lip so as to push said lip toward contactwith the surface of said housing; and outer spring means for maintainingcontact between said outer frustoconical surface and said outer lipwherein said outer loading ring and outer spring means are telescopedover the cylinder portion of said inner loading ring, said shaft sealfurther including support means for axially supporting said outer springmeans.
 2. The shaft seal recited in claim 1 wherein said support meansis an annular member comprising a cylindrical shell telescoped over saidoutwardly directed flange, said cylindrical shell terminating with aninwardly directed annular flange telescoped over said cylindricalportion of said inner loading ring.
 3. An actuator, comprising: ahousing, a cylindrical shaft extending through one wall of said housing,means for moving said shaft relative to said housing, and a shaft sealcomprising; a sealing member having a resilient inner annular lip and aresilient outer annular lip, said inner lip contacting a cylindricalsurface of said shaft and said outer lip contacting a cylindricalsurface of said housing, at least one of said lips being adapted formovable engagement with its contacted surface, said sealing memberhaving an annular wall connecting said lips and axially supported issaid housing; an inner annular loading ring including a cylindricalshell terminated on one end by a frustoconical surface in contact withsaid inner lip so as to push said lip toward contact with the surface ofsaid shaft and terminated on the other end by an outwardly directedannular flange; an inner spring means contacting the outside surface ofsaid flange and supported by a radially oriented surface in said housingwherein said inner spring means maintains contact between said innerfrustoconical surface and said inner lip; an outer annular loading ringhaving a frustoconical surface in contact with said outer lip so as topush said lip toward contact with the surface of said housing; and anouter spring means for maintaining contact between said outerfrustoconical surface and said outer lip.
 4. The actuator recited inclaim 3 wherein the outer loading ring is an annular ring terminated onone end by said frustoconical surface and terminated on the other end byan annular surface normal to the axis of said ring, the normal annularsurface contacting the spring means for said outer loading ring, whichspring means is supported by a support means in contact with saidradially oriented surface.
 5. The actuator recited in claim 4 whereinsaid support means is an annular member comprising a cylindrical shelltelescoped over said outwardly directed flange, said cylindrical shellterminating on its end removed from said radially oriented surface withan inwardly directed annular flange, said inwardly directed flangesupporting the outer loading ring spring means.